A multimedia service application is different from the service in the past that provided only voices and images. Nowadays, it provides various multimedia objects for a service, and can be the combination of audios, videos, natural or synthetic graphics, images, text and other various multimedia objects. It can also be a combination of multimedia service applications. Current protection to this complicated multimedia service application is only performing encryption and protection on transported multimedia objects. This is not good enough. In order to avoid illegal access or piracy during transporting a multimedia service application, a digital rights management protection will be added to the transport stream.
Usually, multimedia protection system encrypts only on transport or delivery. As the encryption and protection mechanism on transport channel is broken, the content of the transported multimedia information may be illegally used. Although a few architectures did encryption and protection on multimedia objects, they cannot perform different combinations of rights protection to individual multimedia object. Therefore, neither the variety for the multimedia service application with different compositions of multimedia objects can be provided, nor the multilayered digital rights management can be performed according to the user's degree of authorization.
The protection mechanism for multimedia information by Microsoft Media 9 Series DRM system is the same as traditional way, as shown in FIG. 1. The protection is made on transport channel. Digital content providers can use license registration and media file encryption to protect their digital rights. For example, digital contents, such as audio or video, are encrypted into “Windows Media Audio format (.wma)” or “Windows Media Video format (.wma)”.
Scrambling system for digital television performs encryption and protection on transport streams too. Therefore, as the encryption and protection mechanism on transport channel is broken, the content of the transported multimedia information may be illegally used. The Advanced Television Systems Committee (ATSC), an international non-profit organization developing voluntary standards for digital television, uses Block Cipher of TDES on transport packet level to perform scrambling, as shown in FIG. 2. The Digital Video Broadcasting Project (DVB) uses Block Cipher first, then Stream Cipher on PES or transport packet level is used to perform scrambling, as shown in FIG. 3.
The DRM technology disclosed by U.S. Pat. No. 6,363,488 of InterTrust allows user to access multimedia information distributed by virtual distribution environment (VDE) only under authorization. Therefore, it emphasizes how to safely transport multimedia information.
The DRM technology disclosed by U.S. Pat. No. 6,381,747 of MacroVision authorizes service provider to encrypt multimedia information. Service provider can change the way of encryption during transport. Therefore, this disclosure emphasizes the encryption and protection during transport.
The decryption key of the DRM technology disclosed by U.S. Pat. No. 6,055,314 of Microsoft can be stored in an IC card. The encrypted multimedia information can be transported safely when consuming, and users can use the decryption key in this IC card for decryption. Therefore, this disclosure emphasizes the encryption and protection during transport too.
The DRM technology disclosed by U.S. Pat. No. 6,530,021 of Philips uses watermarking for copy protection and encrypts the multimedia information with watermarking.
These disclosures emphasize the encryption and protection on multimedia information or the encryption and protection during transport. Even some of them do encryption and protection to multimedia objects in a multimedia service application; their levels of protection are simple and their protections are easy to be broken.
For arts mentioned above, as the encryption and protection mechanism on transporting channel is broken, the content of the transported multimedia information may be illegally used. Also, rights owners or service providers can not set up different levels of DRM protection to each multimedia object in a multimedia service application. They cannot provide the variety for the multimedia service application with different composition of multimedia objects, but only can provide total service to the same level of digital rights management protection. Therefore, they cannot have different levels of usage in the same multimedia service application according to the user's or consumer's degree of authorization.